With gradual popularization of mobile phones, a variety of methods for unlocking a screen of a mobile phone are developed in recent years. Initially, a screen of a key-pressing mobile phone is unlocked by pressing a combination of keys. As for a mobile phone having a touch screen, multiple ways for unlocking a screen, such as by touching the screen along a fixed track, moving an unlocking element to a target area, filling a blank area, etc., are developed gradually. At the same time, techniques of unlocking a mobile phone according to physical characteristics of a human body, such as by identifying a face, a fingerprint, a voice, etc., are becoming well known.
At present, an image can unlock the screen along a predetermined path displayed. A screen is unlocked according to a predetermined gesture when a touch matching the movement of the moving image with a predefined path on the touch screen is detected. This unlocking process cannot be performed unless both an unlocking path and a gesture are prearranged. At the same time, complicated track or target arrangement on an unlocking interface may lead to failure in unlocking by some (particularly elderly) users.
At present, alternatively, once a locked touch screen is touched, a circle centred on the initial point of contact with a radius of a predetermined unlocking length appears on the touch screen. The screen can be unlocked along any path as long as the sliding movement of an operator goes beyond the circled area. However, the screen may be unlocked by mistake due to an accidental screen touch.